Pavement markers with selectively replaceable reflectors



S. A. HEENAN Dec. 23, 1969 3,385, 148 PAVEMENT MARKERS WITH SELECTIVELY REPLACEABLE REFLECTORS 4 Sheets-Sheet 1 Filed June 25, 1968 INVENTOR.

SIDNEY A. HEENAN HIS ATTORN S. A. HEENAN PAVEMENT MARKERS WITH SELECTIVELY REPLACEABLE REFLECTORS 4 Sheets-Sheet 2 Filed June 25, 1968 A I 1. I I. .3?

INVENTOR N M E d E N H R i O A n Y A E B N H D I I s Dec. 23, 1969 s. A. HEENAN 3,485,148

PAVEMENT MARKERS WITH SELECTIVELY REPLACEABLE REFLECTORS Filed June 25, 1968 4 Sheets-Sheet 5 9%, L. flu H RM :7 15 ulk m Mu I m%m% 1 GH n mmm m w. 1 f fr Qs%mmmm% Nx fi mm mm m 2% Dec. 23, 1969 I 51A. HEENAN PAVEMENT MARKERS WITH SELECTIVELY REPLACEABLE REFLECTORS 4 Sheets-Sheet 4 Filed June 25, 1968 gag-BEE a gi QT IiDUEU WQDD E GEMS v i-F mm -Fmfi wa l hwvl INVENTOR SIDNEY A. HEENAN HIS ATTORN nite States Patent M 3,485,143 PAVEMENT MARKERS WITH SELECTIVELY REPLACEABLE REFLECTORS Sidney A. Heenan, Park Ridge, lll., assignor, by mesne assignments, to Amerace Esna Corporation, New York, N.Y., a corporation of Delaware Continuation-impart of application Ser. No. 655,167, .luiy 21, 1967. This application June 25, 1968, Ser.

Int. Cl. Etllc 23/16 US. Cl. 94-15 22 Claims ABSTRACT 0F THE DISCLOSURE A pavement marker for establishing a marking visible from an oncoming vehicle on a roadway surface and utilizing a base member of relatively high strength material, such as a metal, adapted to be atfixed to the roadway surface, preferably through the use of an adhesive, the pavement marker including a reflector body of light-transmitting synthetic resin material atfixed to a portion of the surface of the base member by means which will allow the reflector body to be selectively removed from the base member without destruction of the base member, the reflector body having a reflex reflecting system therein including a plurality of retrodirective reflector elements for receiving light emanating from the oncoming vehicle and incident upon the reflector body in a direction of incidence generally parallel to the roadway surface and refleeting such light to return the light generally parallel to the direction of incidence. The reflector body is preferably in the form of a thin strip having parallel opposite surfaces, one of which surfaces is affixed to a corresponding surface of the base member.

This is a continuation-in-part of application Ser. NO. 655,167, filed July 21, 1967, and now abandoned.

The present invention relates generally to pavement markers and pertains more specifically to roadway traflic rarkers employing reflectors which are cleaned by the action of vehicular tramc on the roadway contacting the marker and which may be replaced with relative ease when worn or otherwise deteriorated.

Pavement markers have become more widely accepted as permanent installations for marking traflic lanes and controlling the flow of traffic on roadways in connection with or in place of conventional painted traflic lines. Because of their greater optical effectiveness and longer life, such markers have found wide use despite the fact that their initial cost has often been greater than the initial cost of conventional painted lines. It becomes apparent, then, that pavement markers which could be less costly to manufacture and which would have an extended life would be even more desirable.

In addition, it has been found that pavement markers which may be optically eflicient for viewing reflected light under nighttime conditions are often severely limited under daytime conditions and cannot be relied upon to provide effective daytime markings. It would be helpful, then, to have available a pavement marker which exhibits an adequate daytime marking, as well as an effective night time marking.

It is therefore an important object of the invention to provide a trafflc marker employing a highly effective retrodirective reflector for establishing a roadway marking visible under nighttime conditions, which traflic marker is selfcleaning in that the reflector is cleaned by contact with the tires of oncoming vehicles.

Another object of the invention is to provide a simplified, ruggedly constructed pavement marker which is economical to manufacture and install and which can pro- 3,485,148 Patented Dec. 23, 1969 vide adequate service for long periods of time with a minimum of maintenance and expense.

Still another object of the invention is to provide a high strength, long lasting pavement marker which will provide roadway markings adequately visible under daytime conditions as well as markings which are effective for nighttime conditions.

The above objects as well as further objects and advantages are attained in the invention which provides a pavement marker for establishing a marking visible from an oncoming vehicle on a roadway surface and includes a base member of relatively high strength material, such as a metal, and has a basal plane adapted to extend parallel with the roadway surface when the base member engages the roadway surface, the base member having a lower surface adapted to be aflixed to the roadway surface and an upper surface rising above the roadway surface when the base member is so aflixed in order to be exposed to oncoming traflic, the lower surface extending longitudinally between a forward portion of the base member adapted to face the oncoming trafiic, an opposite rearward portion and longitudinally extending opposite side portions, the lower surface having an area sufiicient to enable the base member to withstand contact with oncoming vehicles without failure or detachment from the roadway, and the upper surface having at least a first surface portion making an acute angle with the basal plane, a reflector body of light-transmitting synthetic material affixed to the base member and against the first upper surface portion by aflixing means for ready selec tive removal and replacement Without destruction of the base member, the reflector body including an outer surface having an obverse light receiving and refracting face and an inner surface having a reverse light receiving and reflecting face, a reflex reflecting system including a plurality of retrodirective reflector elements of the cube corner type in the reverse face for receiving light emanating from the oncoming vehicle and incident upon the obverse face in a direction of incidence generally parallel to the basal plane and reflecting such light to return the light generally parallel to the direction of incidence, the acute angle between the first upper surface portion and the basal plane being such that the obverse face makes an acute angle of at least 15 with the basal plane, and each of the reflector elements having three planar surfaces arranged mutually at right angles and meeting at a common point remote from the obverse face to form a cube corner, and an axis passing through the cube corner of each reflector element, the reflector elements being oriented such that each cube corner axis makes an acute angle with the normal to the obverse face to align the reflector elements relative to the light refracted as a result of the acute angle of the obverse face for receiving such refracted light and reflecting the refracted light to return the incident light generally parallel to the direction of incidence after refraction of the reflected light at the obverse face.

The invention will be more fully understood and additional objects and advantages thereof will become apparent in the following detailed description of embodiments of the invention illustrated in the accompanying drawings in which:

FIGURE 1 is a perspective view of a pavement marker constructed in accordance with the invention;

FIGURE 2 is a front elevational view of the pavement marker of FIGURE 1 installed on a roadway surface;

FIGURE 3 is a cross-sectional view taken along line 33 of FIGURE 2;

FIGURE 4 is an enlarged fragmentary cross-sectional view of a portion of FIGURE 3;

FIGURE 5 is an enlarged plan view of a portion of the face of the reflector body employed in the pavement marker;

FIGURE 6 is a cross-sectional view taken along line 66 of FIGURE 5;

FIGURE 7 is a perspective view of another pavement marker constructed in accordance with the invention;

FIGURE 8 is a top plan view of still another pavement marker constructed in accordance with the invention;

FIGURE 9 is a longitudinal cross-sectional view taken along line 9-9 of FIGURE 8;

FIGURE 10 is a top plan view of another pavement marker constructed in accordance with the invention;

FIGURE 11 is an enlarged fragmentary cross-sectional view taken along line 1111 of FIGURE 10;

FIGURE 12 is a fragmentary cross-sectional view taken along line 1212 of FIGURE 11;

FIGURE 13 is a top plan view of still another pavement marker constructed in accordance with the invention; and

FIGURE 14 is an enlarged longitudinal cross-sectional view taken along line 1414 of FIGURE 13.

Referring now to the drawings, a pavement marker constructed in accordance with the invention is shown in perspective at 10 in FIGURE 1 and includes a reflector body 12 of light-transmitting synthetic resin illustrated in the form of a relatively thin strip affixed to a base member 16 to establish a rugged structure capable of withstanding forces applied to the pavement marker when the outer surface of the marker is struck by vehicular traflic during service.

The pavement marker 10 is usually employed to provide a marking on a generally horizontally directed roadway surface, the marking being visible from an oncoming vehicle on the roadway surface to delineate traflic lanes. As best seen in FIGURES 2 and 3, the base member 16 is provided with a lower surface 18 coinciding with a basal plane 20 which extends horizontally when the pavement marker 10 is installed upon a roadway surface 22, the lower surface 18 cooperatively engaging the roadway surface 22 upon which the marker is installed. The upper surface 24 of the base member 16 is raised above the basal plane 20 in order to be exposed to oncoming vehicular traflic, the base member having a forward portion or end 26, an opposite rearward portion or end 28 and longitudinally extending opposite side portions or sides 30 and including an upstanding base member portion 32 providing at least a first upper surface portion 34 making an acute angle A with the basal plane 20 and facing the oncoming traflic. The base member 16 is preferably fabricated of a relatively strong material and has been successfully manufactured from metal, either in cast form, in the form of a sheet metal plate, or in the form of an extrusion.

The reflector body 12 is aflixed to the first upper surface portion 34 in such a Way that it will remain aflixed to the first upper surface portion despite the contact made between the tires of oncoming vehicles and the reflector body when the pavement marker is installed upon the roadway. However, it is desirable that the reflector body 12 be capable of selective removal and replacement, when necessary, without the destruction of the base member 16. Hence, in the embodiment illustrated in FIGURES 1 through 3, reflector body 12 is aflixed to the base member 16 by means of an adhesive 36 which will withstand the rigors imposed by placing the 'traflic marker in service yet which will allow selective removal of the reflector body 12 from the base member 16. The pavement marker 10 is fixed in place upon the roadway surface 22 by an adhesive 38, preferably in the form of an epoxy resin which firmly secures the marker 10 at any desired location upon the pavement without requiring any recessing or other disruption of the pavement surface. Thus, it will be seen that once the pavement marker 10 is in place, at least the base member 16 thereof can remain in place indefinitely while the reflector body 12 may be replaced from time to time, as required, in order to provide a beneficially long service life.

Pavement marker 10 is a reflecting type marker and employs a reflecting system to provide a visible marking by receiving light emanating from an oncoming vehicle and reflecting such light back toward the vehicle. In order to provide the necessary visual marking, the reflector system must be initially optically efficient and the marker must be so designed as to maintain the optical effectiveness of the reflector system throughout the useful life of the marker.

One of the most effective reflecting systems available employs the well-known triple-mirror reflex reflecting principle which is thoroughly explained in the Stimson US. Patent No. 1,905,655 issued May 2, 1933, wherein there is disclosed a reflex light reflector including an observe light receiving face and a reverse light reflecting face consisting of a plurality of cube corners, each having three planar surfaces adapted for total internal reflection of light impinging thereon from the observe face. Each of Stimsons cube corners has an axis, and the cube corner axes are parallel to one another. For maximum efficiency, it is usual for such reflectors to be oriented with the cube corner axes essentially aligned with the direction of the nominal incident light. Since the light emanating from oncoming vehicles is practically parallel to the roadway surface at distances where a pavement marker should provide a mark visible from the vehicle. it would at first appear that use of the above described reflector would necessitate having the obverse face of the reflector essentially perpendicular to the roadway surface. It has been observed, however, that such perpendicular surfaces will collect dirt and a light-impeding film will appear, which film will very rapidly reduce the optical effectiveness of such a reflecting system. Thus. some means is required for periodically cleaning the obverse face of the reflector.

It has been discovered that if the obverse face of the reflector system is oriented horizontally, or parallel to the roadway surface, rather than vertically, the normal contact between the tires of passing vehicles and the obverse face will wipe the face clean and the reflector system can retain its optical effectiveness While in service. Unfortunately, however, such contact between oncoming vehicles and the obverse face will also give rise to abrasion of the surface of the obverse face which will rapidly deteriorate the optical quality of the face and reduce the optical effectiveness of the reflector. Such abrasion can be reduced by orienting the obverse face perpendicular to the roadway surface, or in a vertical plane. Thus, on one hand, the obverse face should be oriented toward the vertical to achieve initial optical efliciency and to reduce optical deterioration arising out of contact with oncoming vehicles, but should, on the other hand, be oriented toward the horizontal to allow the face to be periodically wiped clean by such contact. Additionally, a planar face projecting vertically from the roadway surface could become a traffic hazard while a horizontal face would reduce such a hazard.

Pavement marker 10 provides an optically effective reflecting system which remains effective during service and still takes advantage of the wiping action arising out of constant with oncoming traflic. To this end, the marker 10 is provided with a reflector system in the reflector body 12, the reflector system including a generally planar obverse light receiving face 40 on the outer surface of the reflector body and a reverse light receiving face 42 on the inner surface of the reflector body 12. The obverse face 40 is neither vertical nor horizontal, but it is at an acute angle B to the basal plane 20. Since the reflector body 12 is relatively thin and since the outer and inner surfaces of the reflector body extend in generally parallel directions, angle B is equal to angle A.

Acute angle B is chosen so as to be great enough to place the reflector system near enough to the vertical tc be optically effective, but it is also small enough to allow adequate wiping of the obverse face by contact with the tires of oncoming vehicles. Acute angle B is also great enough to reduce optical deterioration of the obverse face arising out of abrasion of the face by such contact with oncoming vehicles. Additionally, angle B is small enough to prevent pavement marker from becoming a traffic hazard.

It has been found that reflector body 12 can be successfully fabricated of a light-transmitting synthetic resin and can thus be molded as illustrated. One such synthetic resin is methyl methacrylate which will exhibit the necessary optical properties and will withstand the constant contact of oncoming traffic during service.

Good results in maintaining optical effectiveness and in achieving adequate wiping action have been attained with an angle B of about 30. Theory indicates and experience has shown, however, that satisfactory results can be realized Where angle B is in the range of to approximately 50.

Referring now to FIGURES 3 and 4, the reflecting system employed in pavement marker 10 is a triple mirror refleux reflecting system in principle, the reverse face 42 of reflector body 12 containing a plurality of retrodirective reflector elements 44 of the cube corner type, each of which is adapted for total internal reflection of light impinging on the reverse face.

Each reflector element 44 has three substantially square planar surfaces 46 arranged mutually at right angles and meeting at a common oint remote from the obver e face 46, thus forming a cube corner 48. Each cube corner has an axis (the diagonal of the cube passing through the cube corner), one of which is illustrated at C in FIG- URE 4. The axes of all cubes corners are parallel to one another although they need not necessarily be parallel.

Light emanating from the head lamps of an oncoming vehicle on the roadway is represented by ray L in FIGURE 4 and is essentially parallel to the horizontal surface of the road. In actuality, the direction of ray L will vary from the horizontal by about only 6 while the vehicle passes through the zone where the reflecting system is required to provide a mark visible from the vehicle. Because obverse face 49 makes an acute angle 8 with the horizontal roadway surface, ray L will be incident upon the obverse face at an angle of incidence i with the normal N to the obverse face and will be refracted upon passage into the material of reflector body 12 at an angle of refraction r as the light proceeds toward the reverse surface 42. Where the index of refraction of the material of reflector body is 1!, light ray L will be refracted in accordance with the following formula:

sin 1," lb

sin 7* and the angle of refraction r can be expressed as:

in ordinary triple mirror reflector structures the axes of the cube corners are aligned parallel with the normal to the obverse face and the obverse face is generally located in a plane which is perpendicular, or very nearly perpendicular, to the nominal incident light so that any refraction which may take place at the obverse face is generally of negligible magnitude. Since maximum ethciency of such a reflector is realized when the light impinging upon the reverse surface is parallel to the axes of the cube corners, maximum efflciency is easily attained in ordinary reflector structures. However, in pavement marker 10, obverse face 40 lies in a plane making a nominal angle of with the horizontal and the angle of incidence i is approximately 60. The angle of refraction 1' then becomes substantial. For example, where reflectory body 12 is molded of methyl methacrylate, u is about 1.5 and the angle of refraction 1' will be about 16. If the cube corner axes were aligned with the normal N to the obverse face as in ordinary reflex structures, the optical efliciency of the reflector system would suffer severely from the large angle of incidence. However, by aligning the cube corner axes of reflector ele ments with the direction of the refracted light rays, that is, at an angle r to the normal N, maximum efficiency of the reflector is maintained despite the rather large angle of incidence.

It is noted that while ideally the cube corner axes should be aligned exactly parallel with the direction of the refracted light rays as computed above for maximum eflficiency, in practice it has been found that adequate performance can be attained when the alignment of the cube corner axis is within about 13 of the computed direction of the refracted rays. Hence, general alignment of the cube corner axes with the refracted light will give rise to satisfactory operation of the pavement marker.

It will be apparent that the angle of incidence will increase with a decrease in angle B, and the greater the angle of incidence, the greater the transmission losses at the obverse face of the reflector body 12, both entering and leaving the reflector body, and the greater the angular error of the return ray caused by small error in the reflecting cube. For optical reasons, then, as well as for the reduction of abrasion arising out of contact with oncoming traffic, it has been determined that angle B should not be decreased below 15.

As stated above, it would be desirable to have available a pavement marker which provides a highly visible mark during the daytime as Well as at night. Daytime visibility is ordinarily provided by random light falling upon the pavement marker structure and being specularly reflected toward oncoming traflic. Unfortunately, the retrodirective reflector elements which provide such effective nighttime visibility will contribute practically nothing to daylight visibility and it becomes necessary to provide some structure which will establish a marking visible under daytime conditions. Hence, in the preferred embodiments, reflector body 12 has been advantageously provided with a construction which provides for the specular reflection of ambient light as Well as the retrodirective reflection of beamed light as described above.

As best seen in FIGURES 5 and 6, the reflector body 12 provides a structure wherein the inner surface is in the form of a continuous support surface interspersed with a plurality of recesses or cells spaced apart from another such that each cell is surrounded by support walls 52 which establish a flat, planar surface portion 54. The reflector elements 44 are located within the cells 50 so that approximately fifty percent of the total area of the inner surface of the reflector body 12 is devoted to retrodirective reflector elements which will provide an adequate nighttime marking while the other fifty percent of the inner surface of the reflector body is devoted to the planar surface portion 54 which will provide for specular reflection of available daylight falling upon the reflector body 12 to render the reflector structure highly visible in daylight. Since the cells 50 and the planar surface portion 54 are dispersed over the entire inner surface of the reflector body 12, the visual effect from the viewing distance is either one continuous area of reflected ambient light under daytime conditions or one continuous area of retro'directed reflected light under nighttime conditions.

Although the illustrated embodiments shows approximately fifty percent of the total area of the inner surface of the reflector body devoted to the flat surface portion 54 and approximately fifty percent of the total area of the inner surface of the reflector body 12 devoted to the cells 50 having reflector elements 44 disposed therein, it has been found that adequate daytime visibility and nighttime visibility may be provided by a reflector structure constructed as illustrated when the area of the planar surface portion 54 includes from about ten percent to about ninety percent of the total area of the inner surface of the reflector body 12 and conversely, when the combined areas of the cells 50 includes from about ten percent to about ninty percent of the total area of the inner surface of the reflector body, the preferred construction being one in which approximately fifty percent of the total area of the inner surface of the reflector body is devoted to the planar surface portion 54 and approximately fifty percent of the inner surface of the reflector body is devoted to the cells 59. In this connection it is noted that in daylight the cells 50 appear dark and contribute essentially no visual signal and conversely at night the planar surface portion 54 appears dark and contributes substantially no visiual signal. It is desirable, as pointed out above, that the reflector body, when viewed from the front at a distance of about one hundred feet or more, appear uniformly lighted throughout the area thereof and appear to be of the same shape both when lighted by daylight falling upon the obverse face 40 in the area corresponding to the planar surface portion 54 for the reflecting of daylight therefrom and when lighted by light from an oncoming vehicle falling upon the obverse face 40 in the area corresponding to the cells 50 for reflecting light back toward the vehicle. To this end the major dimensions of each of the cells 50 as viewed in the obverse face 43 is no greater than about 0.35 inch and the distance between adjacent cells 50 as viewed in the obverse face 40 is no greater than about 0.35 inch. When such dimensions are em ployed, the human eye at one hundred feet cannot distinguish between or resolve the individual elements seen through the obverse face 49, whereby the obverse face appears to be uniformly lighted and of uniform shape both in the daylight when lighted by random light and at night when lighted by the headlights of an oncoming vehicle.

As best seen in FIGURES and 6, the rear of the reflector body 12 is preferably sealed by a backing member 56 which is illustrated in the form of a thin metal foil secured to the planar surface portion 54 throughout the area thereof by a thin film-like coating 58 of heat-sealable synthetic plastic material that is fusion bonded upon both the planar surface portion 54 and the adjacent surface of the metal foil. The metal foil may be formed, for example, of lead or alminum metal, and may have a thickness in the range from about 1 mil to about 5 mils. Further details of such a backing member and the coating may be found in U.S. Letters Patent No. 2,791,938

granted May 14, 1957 to Harold A. Doolittle and Sidney taminants from the cells 50 and thus prevents the deposition of such foreign materials upon the reflecting surfaces of the reflector elements 44, thereby preserving unimpaired the optimum light reflecting properties of these elements. Since the support Walls 52 are all interconnected and thus establish a continuous planar surface portion 54 surrounding each cell 50, each of the cells 50 is individually sealed independent of each and every other cell 50 and any break in the backing member 56 or in the reflector body 12 which may permit the entrance of water, dirt or like foreign material into one cell will not adversely affect other cells which are independently hermetically sealed. Consequently, the reflector structure exhibits greater resistance to weather and greater durability in use, even when the reflector structure is extremely thin, since a break or impairment in one of the cells will not be propagated to adjacent cells. Furthermore, the support walls 52 and the sealed cells provided thereby assure that total internal reflection will take place at the surfaces of each reflecting cube with the concomitant high efliciency of such a reflecting systern. The maintenance of such high efliciency renders practical the allocation of some of the area of the reflector body for specular reflection without drastically reducing the availability of suflicient reflecting ability for nighttime purposes. While it is preferable that the reflector body 12 be ealed by an independent backing member 56, it will be apparent that the planar surface portion 54 may be adhered directly to the first upper surface portion 34 so that the reflector body 12 will be sealed by the surface portion 34 of the base member 16 itself or the adhesive adhered thereto.

Additionally, the support walls 52 extend throughout the area of the inner surface of the reflector body 12 so that when the reflector body 12 is assembled with the base member 16, any forces applied to the outer surface of the eflector body are distributed throughout the area of the reflector body. In other words, there is support for the reflector body throughout the area thereof, the only portion not having direct support being in the individual cells 50. As a consequence, the reflector body 12 has great strength even when the total thickness thereof is only a fraction of an inch.

The coating 58 is transparent, so that the surface of the backing member disposed toward the inner surface of the reflector body 12 is visible, and preferably forms the reflecting surface for reflecting daylight to achieve daylight visibility of the reflector body. Alternately, a light reflecting film such as a metalized film. or a colored film, may be placed upon the planar surface portion 54. It has been found that the use of a white film is exceptionally effective for enhanced daytime ViSlbility.

It will be apparent that the reflector body 12 may be formed of clear synthetic resin material, whereby L white beam of light is reflected both in daylight and at night; however, a color such as red, yellow, blue or the like may be incorporated in the material of reflector body 12, thereby providing a colored signal both in daylight and at night. Alternately, the reflecting surfaces or the reflector body may be colored, to thus give colored reflections.

The reflector body 12 is conveniently mounted upon the base member 16 by means of a suitable adhesive 36. Such an adhesive will allow the reflector body to be selectively removed and replaced without disturbing the installation of the base member 16 upon the roadway surface 22. Among the most successful adhesives employed, both from the standpoint of ease of assembly and durability, are those known as pressure-sensitive adhesives and available commercially in the form of double sided pressure-sensitive adhesive tapes. Such tapes are readily cut to shape and applied to the backing member prior to applying the entire reflector body 12 to the first upper surface portion 34.

Pavement marker 10 is also provided with a second reflector body 69 affixed to a second upper surface portion 62 of the upstanding base member portion 32 and facing the rearward end 28 of the base member 16 at an angle of inclination similar to the angle of inclination of reflector body 12 (see FIGURES 1 and 3), thus rendering the pavement marker bidirectional. Since the second reflector body 60 is entirely independent of the first reflector body 12, each may be made to provide a marking having a color different from the other, thereby allowing the pavement marker 10 to serve as a device for indicating the proper direction of travel on a roadway. Although the illustrated embodiment is a bidirectional device, a monodirectional device is clearly within the purview of the invention and may be constructed by merely eliminating the duplication of the reflector bodies and the attendant mounting structure.

t will be noted that the base member 16 extends longitudinally beyond the extent of the reflector bodies 12 and 60 to establish a relatively large area in lower surface 18. The large area provides adequate load-bearing support to assure that the intermittent contact of vehicular traffic with the pavement marker will not establish stresses great enough to either break the base member 16 or push the base member into the roadway surface, particularly on relatively soft roadway materials.

It is noted that the opposite sides 30 of the base member 16 are inclined inwardly somewhat so as to eliminate, to a great extent, vertical surfaces which could induce excessive shocks upon the tires of oncoming vehicles as the tires pass over the pavement marker 19 and could constitute a traflic hazard.

Turning now to FIGURE 7, another embodiment of the pavement marker of the invention is shown at 110 and has a reflector body 112 of much the same construction as set forth above in the description of reflector body 12. The pavement marker 110 has a base member 116 which is extruded and therefore has a constant crosssectional area along the width thereof. The reflector body 112 is located within a lateral groove 113 in the base member 116 and adhered to the base member in much the same manner as described above.

Included in the extruded cross-section are auxiliary bases 120 which extend across the width of the base member 116 and provide added support for the upstanding portions of the base member, as well as added basal surface area. The basal surface is preferably provided with lateral serrations 122 in order to increase the holding power of the adhesive which will fix the pavement marker to a roadway surface.

Base members such as those shown in the embodiment of FIGURE 7 are economically fabricated in large quantities by merely severing the individual base members from continuous extrusions of indeterminate length. Such extrusions would preferably be made of aluminum.

Turning now to the embodiment of the invention illustrated in FIGURES 8 and 9, a pavement marker 210 is seen to have a reflector body 212 constructed in a manner similar to reflector body 12 of the earlier described embodiment. In the instant embodiment, the reflector body 212 is shown being slipped laterally, or sidewise, into (or out of) a laterally extending channel 214 established in a base member 216 which is fabricated in the form of an aluminum extrusion.

The base member 216 is provided with a lower surface 218 on lower portion 220 of the base member and coinciding with a basal plane which will extend generally parallel with the surface of the roadway upon which the pavement marker 210 is to be installed. The upper surface 224 of the base member is raised above the basal plane in order to be exposed to oncoming vehicular traffie, the base member thus having a forward portion or end 226, an opposite rearward portion or end 228 and longitudinally extending side portions or sides 230.

As in the earlier described embodiments, an upstanding upper base member portion 232 is provided for supporting the reflector body 212 in the desired position with respect to the roadway surface. The upstanding base member portion 232 is braced by means of an upstanding web 233 which extends between upper base member portion 232 and the lower portion 220 of the base member generally perpendicular to the lower portion 220. Lower portion 220 extends continuously and without interruption between the forward and rearward ends 226 and 228, respectively, to provide, along with web 233, a high-strength longitudinal cross-sectional configuration capable of wwithstanding the impace of oncoming traffic.

An upper surface portion 234 lies at the bottom of the channel 214 and provides a surface against which the reflector body 212 is normally affixed. The reflector body 212 is aflixed to the base member 216 by virtue of the interfitting configurations provided in the base member and the reflector body; namely, the laterally extending upper and lower grooves 236 and 238, respectively established in the upper and lower boundaries of the channel 214, and the corresponding upper and lower tongues 240 and 242, respectively, formed as an integral part of the reflector body. These interfitting configurations will allow the reflector body 212 to be slipped into the base member 216 in a sidewise direction (see FIGURE 8) to bring the reflector body and the base member into the desired assembled relationship. When the reflector body reaches the proper position upon the base member, an aperture 244 in the reflector body will become aligned with a similar aperture 246 in the base member so that a fastener member, shown in the form of a rivet 248, may be passed through the aligned apertures 244 and 246 to preclude sidewise movement of the reflector body away from its proper position with respect to the base member.

The pavement marker 210 is also a bidirectional unit and includes a second reflector body 250 which is slipped into place within a second channel 252 in the base member and held in proper position by fastening means in the form of a second rivet 254.

When it is desired to remove the reflector body 212 or 250, the corresponding rivet is removed and the reflector body may be slipped in a sidewise direction until the tongues are disengaged from the corresponding grooves.

Referring now to the embodiment of FIGURES 10, 11 and 12, a pavement marker 310 is shown to have a construction very much the same as that of pavement marker 210, the only exception being that the rivets 248 and 254 and the corresponding apertures in the reflector bodies and the base member have been eliminated. In pavement marker 310, the reflector bodies 312 are slidably received within channels 314 within the base member 316, but are retained in the correct lateral position by fastening means shown in the form of detent means 319 having interengaging detent portions on the reflector body and the base member. Thus, the base member 316 is provided with a downwardly extending projection 320 which normally lies between upwardly extending shoulders 322 which are integral with the reflector body to lock the reflector body in place upon the base member. As best seen in FIGURE 12, a certain amount of clearance 324 is provided between the corresponding tongue 326 of the reflector body 312 and groove 328 of the base member 316 so that the reflector body and base member may be brought into interengaging relationship without resistance over the greatest portion of the length of sidewise travel of the reflector body in the channel 314, the projection 320 being free of the reflector body over such a portion of travel. As the reflector body approaches the desired final position in the base member, the projection 320 will engage one of the gently sloping ramps 330 of the upwardly extending shoulders 322, and the limited resilience of the materials from which the reflector body and the base member are fabricated will enable the projection 320 to pass along the ramp and become engaged between the shoulders 322, thereby locking the reflector body in correct position upon the base member. Removal of the reflector body from the base member is accomplished by exerting suflicient lateral force upon the reflector body to dislodge the projection 320 from between the shoulders 322.

Turning now to FIGURES 13 and 14, still another pavement marker 410 is shown and is seen to be a bidirectional unit having reflector bodies 412 affixed to a base member 416 in the same operating relationship as found in the earlier described embodiments.

In this embodiment, however, a member in the form of a cap 420 extends laterally across the base member 416 and is removably secured in place at the uppermost portion of the base member by means of fastener members shown in the form of screws 422 threaded into a web 424 established in the extruded cross-section of the base member. The cap 420 is urged downwardly against the upper edges 426 of the reflector bodies 412 and secures the reflector bodies in place upon the base member. When it is desired to remove the reflector bodies, the cap may be either loosened or removed, thereby releasing the reflector bodies for removal from the base member.

The cap 420 is preferably fabricated of a synthetic resin material which can withstand contact with oncoming traflic and still exert a retentive force upon the reflector bodies. One such material is nylon such as that commercially available as Zytel 101.

It is to be understood that the above detailed description of preferred embodiments of the invention are provided by way of example only. Various details of design and construction may be modified without departing from the true spirit and scope of the invention as set forth in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pavement marker for establishing a marking visible from an oncoming vehicle on a roadway surface, said pavement marker comprising:

a base member of relatively high strength material, such as a metal, adapted to extend in a direction which will be parallel with the roadway surface when the base member engages the roadway surface;

said base member having a lower surface adapted to be aflixed to the roadway surface, and an upper surface rising above the roadway surface when the base member is so aflixed in order to be exposed to oncoming traflic, said lower surface extending longitudinally between a forward portion of the base member adapted to face the oncoming traffic and an opposite rearward portion, and laterally between longitudinally extending opposite side portions, said lower surface having an area sufllcient to enable the base member to Withstand contact with oncoming vehicles without failure or detachment from the roadway, and said upper surface having at least one flat surface portion making an acute angle with the direction of the longitudinal extent of the base member and having a longitudinal extent less than the longitudinal extent of the lower surface;

a reflector body of light-transmitting synthetic resin material, said reflector body including an outer surface having an obverse light receiving and refracting face and an inner surface having a reverse light receiving and reflecting face;

means aflixing said reflector body to said base member against said one upper surface portion for selective removal and replacement without destruction of said base member;

a reflex reflecting system including a plurality of retrodirective reflector elements in said reverse face for receiving light emanating from the oncoming vehicle and incident upon said obverse face in a direction of incidence generally parallel to the direction of the longitudinal extent of the base member and reflecting such light to return the light generally parallel to the direction of incidence;

the acute angle between said one upper surface portion and the direction of the longitudinal extent of the base member being such that the obverse face makes an angle of at least 15 with said direction;

each of said reflector elements having three planar sur faces arranged mutually at right angles for meeting at a common point remote from said obverse face to define a cube corner, and an axis passing through each cube corner so defined, said reflector elements being oriented such that each said axis makes an acute angle with the normal to the obverse face to align the reflector elements relative to the light refracted as a result of the acute angle of the obverse face for receiving such refracted light and reflecting the refracted light to return the incident light generally parallel to the direction of incidence after refraction of the reflected light at the obverse face: and

means providing flat support portions at locations dispersed throughout the area of said inner surface for engaging said one upper surface portion of the base member and supporting and maintaining at least portions of said retrodirective reflector elements spaced from said one upper surface portion.

2. The invention of claim 1 wherein the reflector body is a relatively thin strip of material and wherein said outer surface and the support portions extend essentially parallel to one another.

3. The invention set forth in claim 1 wherein the alignment of each cube corner axis is within about 13 of the direction of the refracted light.

4. The invention of claim 1 wherein said aflixing means comprises a selectively releasable adhesive.

5. The invention of claim 1 wherein the obverse face makes an angle of from 15 to approximately with said direction.

6. The invention of claim 1 herein the obverse face makes an angle of about 30 with said direction.

7. The invention of claim 1 wherein said inner surface includes a continuous support surface extending substantially throughout the area thereof interspersed with a plurality of recesses spaced apart from one another such that each recess defines a cell surrounded by a support wall, said retrodirective reflector elements being located in said recesses.

8. The invention of claim 7 wherein the reflector body is aflixed to the base member along said continuous support surface.

9. The invention of claim 7 wherein the obverse face makes an angle of from 15 to approximately 50 with said direction.

10. The invention of claim 7 wherein the obverse face makes an angle of about 30 with said direction.

11. The invention of claim 7 wherein the alignment of each cube corner axis is within about 13 of the direction of the refracted light.

12. The invention of claim 1 wherein said affixing means comprises interengaging means having interengaging configurations in corresponding portions of said base member and said reflector body.

13. The invention of claim 12 wherein the obverse face makes an angle of from 15 to approximately 50 with said direction.

14. The invention of claim 12 wherein the obverse face makes an angle of about 30 with said direction.

15. The invention of claim 12 wherein the alignment of each cube corner axis is within about 13 of the direction of the refracted light.

16. The invention of claim 12 wherein the base memher is fabricated in the form of a metallic extrusion having upper and lower portions.

17. The invention of claim 16 wherein the longitudinal cross-sectional configuration of the base member includes a continuous lower portion parallel with said direction and extending without interruption between said forward and rearward portions of the base member and an upstanding Web extending between the lower portion and the upper portion of the base member.

18. The invention of claim 12 wherein said aflixing means includes a cap member extending along the uppermost portion of the reflector body and means removably fastening said cap member to the base member such that said cap member engages and aflixes the reflector body in place upon the base member and may be selectively removed to allow selective removal of the reflector body from the base member.

19. The invention of claim 12 wherein said interengaging means includes upper and lower grooves extending laterally between said sides of the base member and tongues interengaging said grooves such that the reflector body may be moved in a sidewise direction parallel to the 13 direction in which the corresponding tongues and grooves extend to be selectively engaged with or disengaged from the base member.

20. The invention of claim 19 wherein the aflixing means includes fastening means for precluding movement of the reflector body relative to the base member in said sidewise direction when the reflector body is correctly positioned upon the base member.

21. The invention of claim 20 wherein the fastening means comprises a fastener extending through the refiector body and into the base member when the reflector body is correctly positioned upon the base member.

22. The invention of claim 20 wherein the fastening means comprises a detent having a first detent portion on the reflector body and a second detent portion on the base member, one of said first and second detent portions including a projection and the other of said detent portions including a corresponding pair of shoulders between which the projection may be lodged when the reflector body is correctly positioned upon the base member.

References Cited UNITED STATES PATENTS 3,409,344 11/1968 Balint et a1 941.5 XR

JACOB L. NACKENOFF, Primary Examiner US. Cl. X.R. 35067 

